| 摘要 |
PURPOSE:To make the reconstitution of a picture more accurate by correcting the geometric distortion, the distortion in density and the distortion in phase taking into consideration the pre-measured distortions in the static magnetic field distribution and slant magnetic field distribution. CONSTITUTION:A high frequency pulse is transmitted to the body to be inspected from a transmitter 202 by a sequence control part 201. A static magnetic field and slant magnetic field are generated by a magnetic field control part 203 and magnetic field driving part 204 as well. The NMR signal which is from the body to be inspected is received by a receiver 205 and the picture is reconstituted by a processor 206. In this case, the distortion is measured by projecting the grating phantom for measuring a space distortion in advance. Namely the space distortion in the directions x, y is calculated by varying the intensity of the phase encoding slant magnetic field in the direction y, then the slant magnetic field distortion in the direction y is found. The slant magnetic field distortion in the direction x is similarly found by measuring on the direction x. The static magnetic field distortion is calculated from the slant magnetic field distortion in the directions x, y thereof. The imaging can therefore by made more accurate because of the NMR detecting signal being corrected by finding the static magnetic field distribution and slant magnetic field distribution. |
